The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Semiconductor lasers are used in a variety of applications, such as high-bit-rate optical fiber communications. To provide optical fiber communications, lasers are optically coupled to fibers to enable modulated light output from the laser to be transmitted into the fiber. Various modules, assemblies or packages are used to hold and align the laser, other optical components (e.g., collimation and coupling lenses, isolators, and the like), and optical fiber such that the laser is optically coupled to the fiber. The process of aligning an optical fiber to a laser diode and fixing it in place is sometimes referred to as fiber pigtailing. Standard laser package types include coaxial or TO (transistor outline) can laser packages and butterfly laser packages.
In a TO can laser package, for example, the laser (e.g., a laser diode) and the light-receiving end of the optical fiber may be mounted together within a substantially cylindrical housing. The laser may be mounted on a laser submount on the TO can post of the TO can header. The fiber end may be disposed in a rigid cylindrical ferrule mounted to the TO can housing. The TO can housing may also contain other related components, such as a lens and a monitor photodiode, and may be hermetically sealed. A standard TO can housing generally does not contain a temperature control device such as a thermoelectric cooler (TEC).
In a butterfly type laser package, the laser and related components are mounted on a platform such as an optical bench within a metal boxlike housing that is hermetically sealed. These related components may include laser circuitry including signal conditioning and impedance matching circuits, and a temperature sensor. The laser and laser circuitry are electrically connected to one or more pins extending laterally from the housing (e.g., 7 pins on each side). In one type of butterfly type housing, there is an opening in an end sidewall of the housing that receives a metal pipe or ferrule. The fiber is inserted through the ferrule into the inside of the housing and soldered to the ferrule for a sealed fit. Components such as an isolator and one or more lenses may be disposed on the platform between the laser and the input end of the fiber. The optical bench may be mounted on a temperature control device, such as a Peltier effect element or a thermoelectric cooler (TEC), inside the boxlike housing. The TEC is used to control the temperature of the diode laser to permit higher performance and/or operation over a greater power range. For these and other reasons, butterfly laser packages are generally more expensive than TO can laser packages and are generally used for higher performance applications.
The butterfly housing may be mounted onto a larger circuit board, sometimes referred to as a transmitter board or motherboard, which contains external circuitry (such as drive circuitry and other circuitry) and a heatsink in contact with the TEC. The transmitter board contains a mating section designed to receive the butterfly housing. The mating section may be, for example, a rectangular opening in the transmitter board having contact points around the opening on the upper surface of the board. The contact points are located so as to be in contact with the pins extending laterally from the butterfly housing when it is lowered into the opening so that the pins are flush with the upper surface of the transmitter board. Existing TO can housings are generally not designed to be mounted into such mating sections designed for butterfly type housings.